How to know if a variable of arbitrary type is Zero in Golang?

Question

Because not all types are comparable, e.g. a slice. So we can\'t do this

var v ArbitraryType
v == reflect.Zero(reflect.TypeOf(v)).Interface()

Answer 1

As Peter Noyes points out, you just need to make sure you're not comparing a type which isn't comparable. Luckily, this is very straightforward with the reflect package:

func IsZero(v interface{}) (bool, error) {
    t := reflect.TypeOf(v)
    if !t.Comparable() {
        return false, fmt.Errorf("type is not comparable: %v", t)
    }
    return v == reflect.Zero(t).Interface(), nil
}

See an example use here.